Postglacial uplift, neotectonics and seismicity in Fennoscandia

Fennoscandia has experienced major uplift in postglacial time, which is assumed to reflect a glacial isostatic process connected to the melting of the last ice sheets. Extensive modelling of the isostatic movements show that the applied deglaciation and uplift model fit the observations well. There are, however, areas with significant deviations between uplift measurements and regional model predictions. The misfit between observations and the isostatic uplift modelling is interpreted here to reflect a tectonic component of the uplift. The objective of the present investigation is to isolate this tectonic uplift component. Interestingly enough, the areas found partly correspond to areas with pronounced seismic activity, and the assumption that the postglacial rebound is responsible for much of the observed onshore seismicity is substantiated. We conclude that there seems to be present-day deformation along the shoreline of mid-Norway, southern Norway (shoreline and mountain areas), and along the Swedish east coast with the centre northeast of the Gulf of Bothnia that cannot be explained by glacial isostasy. Not all of the deformations in these areas are necessarily co-seismic. The study suggests that such vertical deformations are small in magnitude and overprint the glacial rebound. The deformations map be a consequence of the Plio-Pleistocene erosional pattern, which is of glacial origin. (C) 2000 Elsevier Science Ltd. All rights reserved.